1. Field of the Invention
The present invention relates generally to sewing machine feed conversion apparatus, and more particularly, and not by way of limitation, to an apparatus for attachment to a sewing machine having a bottom workpiece feed mechanism to convert said machine to one having a top and bottom workpiece feed mechanism whereby workpieces of extra thickness can be fed through said machine.
2. Description of the Prior Art
Many various sewing machine apparatus both for domestic use and commercial use have been developed. Generally, sewing machines intended for domestic use include bottom workpiece feed mechanisms. That is, a feed dog is provided positioned in the work supporting surface of the machine which is raised, moved in the direction of feed, lowered, and moved in the opposite direction with each cycle of the needle bar. Such machines also include a presser foot for urging the workpiece being stitched against the work supporting surface so that the feed dog contacts the workpiece and moves it forward when the feed dog is raised and moved in the direction of feed.
Sewing machines intended for commercial use, on the other hand, generally include feed mechanisms which grip the top and bottom surfaces of the workpiece whereby the workpiece can be of extra thickness but still fed through the mechanism and stitched by the machine. Such top and bottom workpiece gripping feed mechanisms usually include a feed dot of the type described above positioned below the workpiece and a feed foot positioned above the workpiece which moves in timed relationship with the feed dog to advance the workpiece. That is, the feed foot is lowered into contact with the top surface of the workpiece at the same time the feed dog is raised into contact with the bottom surface thereof and both are moved in the direction of feed simultaneously so that the workpiece is advanced. Such simultaneous top and bottom workpiece gripping feed mechanisms make it possible for extra thick workpieces or multi-layered workpieces to be advanced and stitched by the machine.
Commercial sewing machines are generally considerably more expensive than domestic sewing machines which include only a bottom feed dog and a presser foot. By the present invention, apparatus is provided which can be attached to a domestic sewing machine to convert the machine to one having a top and bottom workpiece gripping feed mechanism thereby allowing the sewing machine to feed and stitch workpieces of extra thickness at a cost substantially less than that required for the purchase of a commercial sewing machine.